feat: add mcp app renderer (#6095)

Co-authored-by: Douwe Osinga <douwe@block.xyz>
Co-authored-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

ui/desktop/eslint.config.js

@@ -72,6 +72,9 @@ module.exports = [
         HTMLButtonElement: 'readonly',
         HTMLDivElement: 'readonly',
         HTMLCanvasElement: 'readonly',
+        HTMLIFrameElement: 'readonly',
+        MessageEvent: 'readonly',
+        StorageEvent: 'readonly',
         File: 'readonly',
         FileList: 'readonly',
         FileReader: 'readonly',
@@ -143,4 +146,4 @@ module.exports = [
       },
     },
   },
-];
+];